Heating method and means



E. WHITBY ET AL 2,115,601

HEATING METHOD AND MEANS A fil 26, 1938.

2 Sheets-Sheet 1 Filed March 11, 1932 INVENTORS E. Wkz'ibg Ii D. PaZZerZJSeZsZwz 17.18. Easter flJMq/man A RNEY rawn-n O April 26, 1938. E.WHITBY ET AL 2,115,601

HEATING METHOD AND MEANS Filed March 11, 1932 2 Sheets-Sheet? INVENTORSE. PY/zz'iby' ZflflPedZer 3/9 ZYJ'SzZsZwz LElIes Zar BY d Ilka/MnPatented Apr. 26, 1938 UNITED STATES PATENT OFFICE Pedler, Ernest JosephSelston,

and Arthur Joseph Newman, Bristol, and Llewellyn Rolls Lester, OldBracknell, England, assignors to Landis & Gyr, A-G., a corporation ofSwitzerland Application March 11, 1932, Serial No. 598,188 In GreatBritain March 18, 1931 4 Claims. (01. 219-ss) The invention relates to anovel and useful method and means for heating materials in a fluentstate and more particularly to such a method and means for controllingthe tempera- 5 ture of a heated body of fluent material having avariable withdrawal and supply.

Objects and advantages of the invention will be set forth in parthereinafter and in part will be obvious herefrom, or may be learned bypractice with the invention, the same being realized and attained bymeans of the instrumentalities and combinations pointed out in theappended claims.

The invention consists in the novel parts, constructions, arrangements,combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a parthereof, illustrate one embodiment of the invention, and together withthe description, serve to explain the principles of the invention.

0f the drawings:

Fig. 1 is a partially diagrammatic view in transverse vertical sectionof a heater embodying the invention;

Fig. 2 is a similar view of a,,modified form showing anelectrically-controlled make-up valve;

Fig. 3 is a similar view of a modified.form

showing the make-up valve and the heating current controlled by the samethermostat; and

Fig. 4 is a similar view of a fourth modification wherein a make-upstorage tank is eliminated.

The invention is directed to novel means for heating fluent materialssuch as fluids; solids in a flaky, granular, powdered or other fluentform; or mixtures of liquids and solids, which are capable of beingregularly fed to a heating chamber. The invention also comprises a novelmeth- 0d of controlling and maintaining the heat and/or temperature of abody of such materials. The invention is primarily applicable to theheating of fluent materials which are maintained and heated in a heatingor storage chamber from which withdrawals of the hot fluid or the likeare made from time to time and partially or wholly replaced by colderfluid. The replacing fluid is usually termed the make-up and this termwill be so employed hereinafter.

The invention is more specifically directed to improvements in presentmethods and means for electrically heating water, and the hereinafterdescribed embodiment of the invention is an electric water heater,although it will be understood that the broad features of the inventionare also applicable to difierent types of heaters and to the heating andheat control of all materials designated above.

One of the primary objects of the invention is to provide a heater and amethod of heating water or the like so as to prevent substantialreductions in the temperature of the supply of hot water by virtue ofingress of the cold water makeup consequent upon withdrawals of the hotwa ter. In accordance with the invention, the sup ply of the make-up isautomatically controlled, preferably by thermostatic means, so that themake-up fluid is admitted to the heated body of fluid only when thetemperature of said body exceeds a predetermined minimum, and the amountand/or rapidity of admission of the make-up is in proportion to thetemperature and amount of fluid in the heated body, so that thepredetermined temperature thereof may bemaintained substantiallyconstant at all times. By thus regulating the ingress of make-upindependently of the outflow or withdrawal of the heated fluid, thetemperature of the latter can be maintained substantially as desired andthere is never any appreciable cooling 01f of the heated fluid,regardless of the frequency of the withdrawals.

More specifically, the present preferred embodiment of the inventioncomprises an electric water heater for heating a body of water in astorage tank or container, the heater having its circuit controlledthermostatically, whereby the heating current will be cut off when thetemperature of the body reaches the predetermined maximum and will beswitched on when the temperature falls substantially below said maximum.The make-up water supply is connected with the heating and storagechamber by a thermostatically-controlled valve which is responsive tothe temperature of the heated body of water. This valve is so controlledthat cold make-up water will be admitted to the heating chamber onlywhen the temperature of the heated body exceeds a predetermined minimum,and thereafter the admission of the make-up will be at a rate and for atime dependent upon the amount required to maintain the desiredtemperature and quantity of the heated water.

Furthermore, the invention is especially applicable to electric supplysystems with restricted hours of supply for water heating purposes, suchas those having heaters of the off-peak type,

Hence if any fluid is drawn off during the time when the supply currentis switched off from the heater circuit, the temperature of this fluid,apart from radiation losses, is at the desired temperature and cannot belowered by the inflow of cold make-up.

It will be understood that the foregoing general description and thefollowing detailed description as well are explanatory and exemplary ofthe invention, but are not restrictive thereof.

Referring now in detail to present preferred embodiments of theinvention, in Fig. 1 there is shown a heater of the type in which themakeup inlet valve is mechanically coupled to and operated by athermostat. In accordance with the invention a cistern or water tank Iis preferably formed with an inner heating and storage chamber 2 forcontaining and heating the body of hot water. The cistern preferably isconstructed with an outer shell or casing and the space between it andthe inner chamber 2 is preferably filled with suitable insulatingmaterial 3, as shown.

The embodied means for maintaining a supply of cold make-up watercomprises a feed trough or tank 4, preferably mounted above the storagetank 2 as an integral part of the main cistern I, the tanks 2 and 4being suitably insulated from each other as shown. Cold water issuitably admitted to the feed trough 4 through inlet pipe 6 which may beconnected to a cold water supply main, and admission of the cold waterto the trough is controlled by a suitable valve 5 which is responsive tothe level of water in the feed trough by means of the float 5a and theconnecting lever 5b. A suitable overflow pipe I is provided in the upperportion of the trough 4.

Means are provided for heating the body of water in the tank 2 and forcontrolling the maximum temperature of the water, comprising anelectrical heating element 9 and an over-temperature thermostat I 0which are suitably connected to the heating circuit I5 in a well-knownmanner, so that the thermostat controls the circuit switch (not shown).The heater 9 and thermostat II] are preferably disposed relatively nearthe bottom of the tank, so that they will always be immersed in water.For this purpose, the draw-off tap 8 is mounted substantially above thebottom of the tank and slightly above the level of the thermostat I0 sothat a small amount of water, as shown, will always be maintained in thetank and immersing the heater and thermostat.

In accordance with the invention, means are provided for admittingmake-up water from the trough 4 to the heating chamber 2 only when thetemperature of the heated water reaches or slightly exceeds apredetermined minimum. As embodied, a supply tube II is provided betweenthe trough 4 and the chamber 2 and passage of water from the tank 4through the tube is controlled by a tapered valve I2, which is movableaxially with respect to the tube I I and is mounted on the upper end ofthe tube-enclosed rod I3 as shown. The embodied means for raising andlowering the valve I2 comprises a thermostat I4 which is connected tothe rod I3 at its lower end and near the bottom of tank 2. Thethermostat may be of a known bi-metallic type, with the bimetals coiledinto a spring to which the valve rod is attached and the connections soadjusted that the valve begins to lift at the desired and predeterminedtemperature. The thermostat may also be made up of inter-acting stripsor plates, as

shown, which by their differing coeflicients of expansion perform thesame function; or it will be understood that the thermostat may be ofany known or suitable construction adapted to impart the desiredmovement to the valve rod I3.

The operation of the mechanism shown in Fig. 1 may be briefly describedas follows:

When current is firstswitched on, the heating element 9 heats up theliquid until the temperature attained is that at which the thermostat I4has been set to act. The thermostat I4 then by expansion causes thevalve I2 to open to a certain extent and thus permits the ingress ofcold water which mixing with the hot water causes cooling of the watersurrounding the thermostat I4, thereby causing contraction of thebimetallic element and consequent closing of the valve I2. The coldwater that has thus been permitted to enter the hot water tank lowersslightly the temperature of the water in the tank, but as the heatingelement 9 is in operation, the water is quickly heated up again untilthe temperature is such that the expansion of the bimetallic elementagain causes the valve I2 to operate and permit the entry of furtherwater into the hot water tank 2.. This procedure continues untilgradually the hot water tank is completely filled with hot water of thedesired temperature for which the thermostat I4 has been set. Should thewater then continue .to rise in temperature, the overtemperaturethermostat II] will come into operation and automatically switch off thesupply of current to the heating element 9, which supply will remain ofiunless the temperature of the water should fall below the predeterminedfigure when the thermostat I0 will switch on the electric current,whereby the temperature will again be raised to the desired degree.

Should hot water be drawn oif from the tank by means of the tap 8, coldwater make-up will first flow out of the feed trough 4 through the feedpipe II into the hot water container 2, whereby the water surroundingthe thermostat I4 will have a lower temperature, so aifecting thisthermostat that it will close the valve I2 thereby preventing the entryof further cold make-up until the temperature of the water in thestorage chamber has been brought up again, when the thermostat I4 willagain open the valve I2 and the operation of the valve in this mannerwill continue until the tank 2 is again full of hot water at the desiredtemperature.

Although in the figure the thermostat I4 and the valve I2 controlled bythe thermostat are shown at opposite ends of the tube II the valve canbe placed in any suitable position other than that indicated. Thethermostat I4 can be placed in any position suitable for its beingappropriately aifected by the temperature of the water in the storagecontainer.

Although in the above description it has been stated that the valveeither opens or closes under the action of the thermostat the valve maybe constructed so that it takes up a balanced position proportionate tothe rating of the elements, and the temperature of the incoming water.

Referring now to the modified form of the invention shown in Fig. 2, aheater generally simi lar to that hereinbefore described in connectionwith Fig. 1 has the make-up controlling valve electrically actuated inresponse to the movements of the thermostat. In Fig. 2 and in thesucceeding figures, parts similar to those described in connection withFig. 1 are given the same reference numerals. As embodied, the valve II2 is seated for vertical movement with respect to the angled inlet tubeIII as shown. The stem I9 of the valve extends upwardly from the valveseat through a tube or casing I20 and into a water-tight chamber I2Iformed in the portion of the make-up trough 4 directly above the valve.The valve stem I9 constitutes the core of a sole- .noid I8 which is thusadapted to actuate the valve I I2 and control the movements thereof.

In accordance with this embodiment of the invention, the solenoid iselectrically controlled by a thermostat II4 which is responsive to thetemperature of the water in the heating chamber 2. Thermostat I I4 ismaintained in a suitable casing H5 in the lower part of the heating tank2 and thereby immersed in the heated water. The thermostat is adapted tocontrol a switch in the enerheating element 9. When the temperature ofthe hot water falls below the predetermined limit, thermostat II4 willbreak the contact at I6 and the solenoid I will be de-energized. therebyclosing valve II2 until the temperature of the water again has beenraised sufllciently to re-actuate the thermostat. A sequence ofoperations, similar to that hereinbefore described in connection withthe embodiment of Fig. 1, will then take place until-the tank is full ofhot water within the predetermined temperature limits.

A further modification of the invention embodies the novel principle ofcontrolling both the maximum temperature switch for the water heatingcurrent and the operation of the valve regulating the inflow of make-upwater. As shown in Fig. 3, a single thermostat, responsive to thetemperature of the heated body of water is adapted to open the make-upwater valve at a predetermined minimum temperature and to open theheating circuit when the water temperature rises to the predeterminedmaximum. As embodied, two electric heating units 209 are mounted at thebottom of the tank 2 and between them a thermostat 2I4 which, throughrod 2I3, actuates the make-up water valve 2I2. The rod 2I3 is extendedabove the valve and into the switch box 200 on the top of the cistern I.A switch, comprising the bridge piece 20I, formed at the upper end ofrod 2I3, and two upwardly-urged spring contacts 202 are mounted in theswitch box. The switch 20I-202 controls the circuit 203 for the heatingunit 209.

In the operation of this device, the valve 2I2 and the circuit 203 willremain closed until the temperature of the water in tank 2 rises abovethe predetermined minimum. When the temperature has reached this minimumlimit, the valve 2I2 will open and makeup water will be admitted to thetank in proximity to the heating units 209 and thermostat 2I4. Theheating circuit however remains closed, because the spring contacts 202follow the bridge 20 to some extent in its upward movement. Whensufiicient makeup water has been admitted to the heating tank to lowerthe temperature, valve 2I2 will again close and this sequence ofoperations will be repeated until the tank 2 is filled with hot water,all without interrupting the flow of current to heating units 209.

When the temperature of the water finally reaches the predeterminedmaximum, the thermostat 2I4 will be deflected sufiiciently to raisebridge 20 beyond the limit of movement of the spring contacts 202 andthe supply of current to the heating elements will thereby be cut offand will remain off until radiation losses or other causes lower thetemperature of the stored hot water sufliciently to cause a closing ofthe switch.

In all of the hereinbefore described heaters, a vent pipe I00 may beprovided between the top of tank 2 and the space above the level of thetank 4. A further modification is shown in Fig. 4, wherein the heatingand control devices operate generally similarly to those shown anddescribed in connection with Figure 1, but wherein the separate tank ortrough for the cold make-up water is dispensed with. In this form, thecurrentsupply circuit 300 of heating unit 3 I9 is controlled by amaximum temperature thermostat 30I through a switching arrangement 302,which is generally similar in construction to that shown in Fig. 2 forcontrolling the solenoid.

The make-up water is admitted directly from the cold water main 5, thevalve 305 being controlled by a minimum temperature thermostat 306acting through a sliding rod 301 and a bell crank lever 308. The valve305 is independent of and in series with the float-controlled valve 5.,

In operation, assuming the tank 2 to be only partially filled; theswitch 302 closed; the float lever b in its lowermost position as shown;and the valve 305 controlled by the thermostat 306; the sequence ofoperations is the same as that in the heater shown in Fig. 3, so long asthe tank is only partially fllled. However, when the level of the waterin tank 2 nears the top of the tank, the float lever 5b will begin torise and will ultimately close the valve 5 and thus prevent furtherentrance of make-up. Then the heating of the water will continue untilthe temperature has risen sufliciently to cause the over-temperaturethermostat 30I to open the switch and cut oif the current to the heatingelement.

The invention in its broader aspects is not limited to the specificsteps and mechanisms shown and described but departures may be madetherefrom within the scope of the accompanying claims without departingfrom the principles of the invention and without sacrificing its chiefadvantages.

What we claim is:-

1. A mechanism for heating water including in combination a containerfor a body of. water, means for drawing off water at a predeterminedlevel near the bottom of said container, heating means acting on thewater below said predetermined level, a feed water reservoir supplyingwater to said chamber by gravity, a valve at said reservoir, athermostat in, said container below said predetermined level, andconnections from said thermostat to said valve for controlling theadmission of water from said reservoir to said container, and separatethermostatic means for controlling the heating means.

2. A mechanism for heating water including in combination a containerfor a. body of water, means for drawing off water at a predeterminedlevel near the bottom of. said container, heating means acting on thewater below said predetermined level, a feed water supply for saidcontainer, a valve in said supply for admitting feed 7 water to thecontainer, a thermostat in said container below said predeterminedlevel, anJi fifitric circuit controlled by said thermostat, andvanelectromagnet in said circuit, and connected to control said valveandn-separate thermostatic means for controlling the heating meansz- 3.A mechanism for heating water including in combination a container for abody of water, means for drawing off water at a predetermined level nearthe bottom of the container, electric heating means acting on the waterbelow said predetermined level, a feed water supply, thermostatic meansin the chamber below said predetermined level for controlling theheating means circuit, and valve means for regulating admission of feedwater to the container, and thermostatic means controlling said valvemeans, the valvecontrolling thermostat being conditioned to open andshut the valve at temperatures lying within the range of thecircuit-opening and closing temperatures of the heater thermostat.

4. A mechanism for heating water including in combination a containerfor a body of water, means for drawing off water at a predeterminedlevel near the bottom of the container, electric heating means acting onthe water below said predetermined level, a feed water supply, andthermostatic means located in the lower part of the container forcontrolling the action of said heating means and for electromagneticallycontrolling the admission of water from said supply means, thethermostatic control of the water supply being adapted to admit and shutoff feed water to the container at temperatures lying within the rangeof the circuit-opening and closing temperatures of the heaterthermostat.

ERNEST WHITBY.

IVOR AUGUSTUS DURANT PEDLER. ERNEST JOSEPH SELSTON. ARTHUR JOSEPHNEWMAN. ILEWEILYN ROLLS LESTER.

